Wireless transmission technology is a known technology for transmitting signals or energy between electrical devices not directly connected by wiring.
In the transmission and reception of signals between high frequency semiconductor chips and external devices, uncertain parasitic capacitance or parasitic inductance occurs when transmission lines are provided using wiring bonding, which affects the characteristics of the high frequency signal. Wireless transmission technology, which does not negatively affect the characteristics of high frequency signals, is used for this reason.
The electronic circuit element known as a digital isolator is one example of a known wireless transmission apparatus which uses wireless transmission technology (for example, see Patent Literature (PTL) 1). The technology disclosed in PTL 1 allows for the ground for logic signals and the ground for RF signals to be isolated, and as such, is widely applicable.
This kind of wireless transmission apparatus is used as, for example, a gate driving element, such as an insulated gate bipolar transistor (IGBT), which is a power electronics semiconductor switching device. More specifically, this kind of wireless transmission apparatus is used in inverter systems or matrix converter systems, which convert DC electricity to AC electricity of a given frequency.
With this kind of power semiconductor switching device, due to fluctuation in source potential with reference to high voltage, it is necessary to insulate the DC component between within the gate driving element and the power semiconductor switching device. For this reason, in this kind of power semiconductor switching device, a wireless transmission apparatus capable of ground isolation is used to drive the gate.
Moreover, electromagnetic resonance couplers (also known as electromagnetic field resonance couplers) which employ the coupling of two electric wiring resonators are one example of wireless transmission technology that has gained attention in recent years. (for example, see PTL 2, Non-Patent Literature (NPL) 1). These electromagnetic resonance couplers are characterized by an ability to efficiently transmit signals across a great distance.